I will be speaking with my agent more on this as we get into the renter/investment side next (just put in an offer on a primary residence today).
Sounds like the online resources are the local paper and Craig's List for me to check online before he does what he does then. It would be nice to have a rental search tool that allowed you to list the address of a potential property, bed/bath/sf counts, exposure, floor level, amenities, and then set a radius to search for the comps. That would be the golden egg. :)